Different binder systems have been used in the manufacture of fiberglass insulation, including phenolic-based binders and polycarboxylic acid binders. The use of phenolic-based binders allows the extent of curing of the binder system to be judged by visual observation, as the appearance of the fiberglass changes as the binder cures. The use of polycarboxylic acid binders such as polyacrylic acid binders, however, does not allow the extent of curing of the binder to be judged by visual observation, as fiberglass insulation manufactured with polycarboxylic acid binder maintains the same or a similar appearance regardless of the extent of cure of the binder.
Fiberglass insulation with binder that is insufficiently cured exhibits poor mechanical performance. Therefore, it would be desirable to provide a method of determining the degree of cure of fibrous products such as fiberglass insulation that include a polycarboxylic acid binder such as a polyacrylic acid binder.